In an autonomous positioning scheme in which a positioning device autonomously determines a position by using code information of a GNSS (Global Navigation Satellite System) signal from a satellite positioning system (GNSS) such as a GPS (Global Positioning System), a positioning accuracy is on the order of meters due to an error included in the GNSS signal.
In comparison with the autonomous positioning scheme using the code information, a positioning scheme using correction data of carrier phase information realizes highly accurate positioning on the order of centimeters. In particular, there is a scheme called an RTK (Realtime Kinematic) scheme or a network-type RTK scheme in which a GNSS signal is received at a plurality of electronic reference points (distributed at intervals of ten or so kilometers in Japan), the accurate positions of which are already known, to estimate an amount of error included in the GNSS signal inversely from the known positions of the electronic reference points, distribute it to a user as correction data, and perform positioning on the order of centimeters together with a GNSS signal acquired by a positioning device on the user's side (Patent Literature 1, for example).
On the other hand, the highly accurate positioning on the order of centimeters is also realized in a positioning scheme that uses an artificial satellite such as a quasi-zenith satellite to distribute correction data valid in a wide area nationwide. In this positioning scheme, the correction data is distributed from the quasi-zenith satellite to allow a positioning device to acquire the correction data even in an environment where communication via a wireless LAN, a mobile phone, or the like is not available. Then, the correction data is used to eliminate the error in the GNSS signal, so that the highly accurate positioning on the order of centimeters can be realized. In such a scheme that uses an artificial satellite to distribute correction data, the data capacity of a satellite circuit is limited, and thus the correction data is distributed in a state amount (State Space Representation) format or a vector format with a view to efficient distribution. Such a scheme using correction data to perform positioning on the order of centimeters is called an RTK (Realtime Kinematic)-PPP (Precise Point Positioning) scheme in “RTCM STANDARD 10403.2”, for example (Patent Literature 2, for example).
In the RTK-PPP scheme, it is possible to perform positioning on the order of centimeters using positioning correction information (correction data) included in an SSR message as defined by “RTCM STANDARD 10403.2”, for example.
However, a receiver of a generation supporting “RTCM 10402.3” cannot perform the positioning on the order of centimeters using the positioning correction information included in the SSR message as defined by “RTCM STANDARD 10403.2”.